Measurement of deformation using
markers enables most accurate results also with difficult measuring and
environmental conditions. The high accuracy of the measuring systems up to
class 0.2 is also a result of good marking. The figures below show the
requirements of a good marking.

Markers have to be parallel to each other

Markers have to be aligned perpendicular to the centre line (loading direction)

Markers should be have sharp edges, similar to foil cutted by a scalpell

Markers have to stick also at large strains and should be following the
deformation of the specimen as required